ES2774929T3 - Energy recovery device over broad wave spectra - Google Patents

Abstract

Wave energy recovery device that includes a hollow structure (1) intended to be maintained above the surface of an area of water, communicating an interior volume of the structure (1) with a turbogenerator group (9, 10) , the structure (1) being associated with a multiplicity of hollow tubes (2) open at their lower ends that are immersed in the water, each tube (2) having a first one-way flap (13) that opens from inside the tube ( 2) towards the interior volume, and a second unidirectional flap (11) that opens from downstream of the turbogenerator group (9, 10) towards the interior of the tube (2), to form an energy recovery loop that works in columns of oscillating water, in interaction with the turbogenerator group (9, 10), characterized in that the structure (1) comprises a lower box (6) and an upper box (5) superimposed, flat, compact, substantially non-deformable, closed and full of a gas, why the tubes (2) go through the lower drawer (6) and flow into the upper drawer (5) and because the turbogenerator group (9,10) is mounted in a passage that interconnects the two drawers (5, 6), allowing the first clapper (13) of a tube (2) that the gas that is above the water is expelled from the tube (2) towards the upper drawer (5) due to the rise of the water level (14) in certain tubes under the effect of a wave, passing the gas thus expelled through the turbogenerator group (9, 10), then returning downstream to the lower drawer (6) to be admitted by suction, by means of the second flap (11), in the tubes (2) for which the water level (12) is descending.

Description

DESCRIPTION

Energy recovery device over wide wave spectra

The present invention relates to a device that allows the recovery of energy from waves, or swell and, more generally, from any dynamic and local fluctuation of a statistical order that moves the surface of any large water plane subjected to the effects of inclement weather.

The proposals that allow the recovery of part of the wave energy in view of its conversion into electrical energy have been multiple in the last twenty years.

The state of the art comprises, to date, five main families of such devices that convert a fraction of the wave energy into rotational mechanical energy, which allows the production of electric current thanks to a generator. Each of these families has its limits and drawbacks.

There are overflow devices, for example those of the international patent document WO 1996/000848. These create a difference in the height of the water by causing the waves to break over the walls of an enclosure whose upper end is situated at an altitude significantly higher than the average level of the water plane. The interposition of a turbine in the water vein that returns from the enclosure to the sea allows the production of electricity thanks to this difference in water height. This simple device, with no other moving mechanical parts other than the turbine, nevertheless presents very low production levels with respect to the dimensions of the occupied space and the investment required. Indeed, only the spectral components of the wave that have a height greater than the overflow height contribute a fraction of energy to the device. Components at small wavelengths, whose height is smaller, are not exploited. An overflow head cannot be chosen too small because it directly sets the recoverable potential energy per volume of water admitted. On the other hand, the turbine for converting the potential energy of the water thus recovered into electricity is necessarily submerged and consequently presents all the additional design, construction and maintenance costs associated with this submerged nature.

There are devices with bottom-attached floats, for example that of US patent US 6,140,712. These devices operate hydraulic pump systems, due to the effect of the forces developed by the rise and fall of the floats, induced by the passage of the waves. These devices inevitably include complex mechanical parts as well as necessarily submerged hydraulic equipment, which present high design, manufacturing and maintenance costs. On the other hand, their inertia does not allow them to recover the energy of the components of short wavelength wave spectra. On the other hand, their implementation, as well as their dismantling, generally require consequent underwater work of a particularly high cost. A variant of this type of device consists of a raised oscillating arm, at the end of which is arranged a semi-submerged float and whose articulation actuates a hydraulic jack when the height of the float varies under the effect of the waves. This device is implanted on a structure that is attached to the bottom or the coast, or even on a highly stable floating platform. This variant does not allow energy recovery other than in the immediate proximity of its support, that is, a modest occupied space.

There are semi-submerged surface attenuators, for example those of the international patent document WO 2011/061546. These devices are made up of a succession of floating works connected to each other by joints equipped with hydraulic jacks. These jacks allow the recovery of energy by putting a hydraulic fluid into circulation at each relative movement of one element with respect to the other. The energy is then converted into rotational mechanical energy by a turbine arranged on the hydraulic circuit. These lines of articulated floating elements are generally anchored at one end, so that in the absence of current, they are oriented freely according to the main wave propagation direction. Their efficiency is maximum when they are subjected to a unidirectional, monochromatic wave with a wavelength close to twice the individual length of an element and it decreases sharply as the wavelength of the wave moves away from this value. Such devices are, on the other hand, not very effective in the case of conjugated or crossed waves, as well as if the main direction of the waves does not coincide with the direction of a possible local current, which then determines the orientation of the device independently of the direction. of the swell. On the other hand, its construction and maintenance costs are high due, on the one hand, to the fragility of the joint systems and, on the other, to the internal hydraulic equipment through which the recovered energy passes before being converted. in electricity.

There are also swing shutter devices, for example that described in US patent document US 2008/0191485. Such devices are made up of shutters that hinge on a base fixed to the bottom. Each shutter oscillates under the effect of the surf-induced undertow. The movement of the shutter activates hydraulic jacks that set a fluid in motion which, in turn, drives a turbine. A variant of this family of devices is constituted by oscillating shutters, the upper part of which includes a float located near the middle level of the water plane. This allows a conjugate recovery of kinetic energy and potential energy relative to the wave of the wave. These devices fixed to the seabed can only be implanted in the immediate proximity of the coasts and on deep sites little. They are effective only for a swell of a fixed wavelength, in a direction perpendicular to the axis of rotation of the shutters, and with a period consistent with their own mode of oscillation. Its effectiveness decreases very significantly as soon as the wave spectrum moves away from this ideal configuration or in case of crossed waves.

There are still devices with oscillating water columns or pistons, for example, that of the international patent document WO 2015/102547 or that of the British patent document Gb 2429 243. Such a device recovers energy, not activating an intermediate hydraulic system , but from the flow of air expelled or sucked in by a column of water moved by the waves. Certain devices are based on cylinders in which pistons move that separate the water from the air. Other devices of this type are constituted by a cavity arranged on a shore subjected to the waves, the lower part of which, permanently submerged and freely open, allows the water to forcefully enter the cavity with each wave. The air in the cavity is then expelled through an alternative flow turbine of the Wells type, which allows the recovery in the form of electrical energy of a fluid that alternately stops in one direction or another. Indeed, when the wave withdraws, the water descends again in the column, generating an aspiration of air from the atmosphere which passes in the opposite direction in the turbine. This type of device can only be installed on a shore whose topography is adequate. Such shores are rare. On the other hand, the alternative air flow requires the use of a Wells type alternative flow wind turbine whose performance is significantly lower than the performance of a unidirectional and regular flow turbine.

A variant of this device is made up of a row of bottomless drawers incorporated into a fixed or floating sculpture. The base of the drawers is submerged, while the upper part of each drawer is in communication with two lateral air collectors fitted with clappers. The direction of opening of the flaps is such that the air pushed by the water that rises in a drawer as a wave passes is expelled into one of the collectors, while another symmetrical collector feeds the drawers with air and / or water level comes down. A wind turbine is installed over a vein that connects the two collectors at the end of the row of drawers, thus moved by a unidirectional air flow. These devices do not allow to recover the energy of the wave components whose wavelength is less than or close to the length of each box. They do not allow efficient energy recovery other than for spectral components of the wave oriented in the same direction as the row of boxes.

Among the water column devices, French patent document FR 2 959 780 describes a device for recovering energy from waves. This device includes a hollow structure intended to be maintained above the water surface with an interior volume of this structure that communicates with a turbogenerator group. The structure is associated with a series of aligned tube curtains, open at their lower ends, which are submerged in the water. Each tube has a first one-way flap that opens from the inside of the tube to the interior volume and a second one-way flap that opens from the outside of the device to the inside of the tube to form an energy recovery device that operates on oscillating water columns. .

Applicant strives to improve this genre of devices.

According to what is proposed:

a hollow structure comprises a lower drawer and an upper drawer superimposed, flat, compact, substantially non-deformable, closed and filled with a gas.

- a multiplicity of tubes equipped with two flaps in their upper part and which pass through the lower drawer and lead to the upper drawer, and

- the turbogenerator group is mounted in a passage that interconnects the two drawers.

In operation, the first clapper allows the expulsion of the gas that is above the water towards the upper drawer due to the rise in the water level in certain pipes under the effect of a wave; The gas thus expelled passes through the turbogenerator group, then returns downstream to the lower drawer to be admitted by aspiration in the tubes for which the water level is decreasing.

Other characteristics, details and advantages of the invention will appear on reading the detailed description that follows and the attached drawings, in which:

figure 1 shows an example of embodiment of a device according to the invention;

figure 2 shows a sectional view of the device of figure 1;

- figure 3 shows a cut away view of a detail of the invention;

Figure 4 shows an example of embodiment of a module of a device according to the invention.

The drawings and the description that follow contain, essentially, elements of a certain character. They may, therefore, not only serve to better understand the present invention but also contribute to its definition if necessary.

By "flat" drawers is meant, specifically, drawers that have a small height compared to horizontal dimensions such as the width and length of the device. By "compact" drawers is meant, specifically, a set of drawers that has a width of the same order of magnitude as its length. In horizontal section, the caissons can be discoidal or square or ellipsoidal, as opposed to the “dike” or “aircraft carrier” style, the elongated shapes being inevitably optimized with respect to a specific direction of the wave, while the invention aims to exploit a broader spectrum of waves (in directions and frequencies, including “multiple” or “stationary” waves). However, it could be otherwise if the device has a mission to navigate.

These proposals improve the known oscillating water column devices to make them more efficient in varied wave conditions, mainly as a function of their wavelengths and the orientation in space of their spectral components.

From another point of view, the device according to the invention comprises a framework made up of a large number of analogous tubes, distributed over a surface of small elongation, that is, with a width of the same order of magnitude as the length, which therefore form Therefore, a volume that is called here "compact". The tubes can extend substantially parallel to one another and perpendicular to their distribution surface. They can be identical or of variable diameters while remaining substantially identical, at least statistically, that is to say, there is a range of diameters, distributed around a mean or nominal value. The lower part of each tube is open and plunges into the water and the upper part is embedded in a structure formed by two superimposed drawers of small heights.

Reference is now made to Figures 1 to 3. An embodiment of the device according to the invention comprises a hollow structure 1 and hollow tubes 2. The hollow structure 1 includes an upper drawer 5 and a lower drawer 6.

The top of each tube 2 includes at least two one-way flaps:

- a first intake flap 13, here a swing top flap, which allows the air repelled by the rising wave front to be expelled to the first drawer, here the upper drawer 5, and

- a second return flap 11, here the lower swing flap, which allows the air from the second drawer, here the lower drawer 6, to be admitted into the tube 2 when the water level locally surrounding the tube 2 drops.

The intake and return flaps 11 and 13 are arranged to open under the effect of small pressure differences and allow the highest possible flow rates. They are also chosen so that the pressure losses are comparable in the intake and in the return.

The two drawers 5 and 6 are connected to each other by a passage in which a turbo-generator group 9, 10 is mounted. The turbo-generator group 9, 10 comprises a classic wind turbine 9, designed to always rotate in the same direction and which drives the current generator 10 that allows energy recovery.

In the example of Figures 1 and 2, the device is a floating version. The hollow structure 1 presents a circular occupied space and then forms a floating platform. Here, the structure 1 has a diameter of around 100 meters for a height between an upper face and a lower face of around 5 meters.

The passage in which the turbogenerator group 9, 10 is mounted takes the form of a duct 3 in the shape of an inverted "U", built in the superstructure and mounted on the upper drawer 5. As shown in the right part of figure 2 , the portion of the duct 3 downstream of the turbogenerator group 9, 10 traverses from part to part and in a sealed manner the upper drawer 5 to open into the lower drawer 6. The duct 3 includes a working portion 4, of reduced section with respect to to the rest of the duct 5, in which the wind turbine is installed.

The upper parts of the tubes 2 are embedded in the hollow structure 1. They pass through the lower drawer 6 to the upper drawer 5. In the example described here, the device comprises a forest of 2,500 to 3,000 tubes 2, with an individual diameter of about 1.2 meters and having lengths of about 11 meters from the lower face of the lower drawer 6 to its lower submerged end, to which is added at least the height of the lower drawer 6, here about 2, 5 meters. The mesh of the tube framework 2 is not strictly regular. The effectiveness of the device is ensured even with an implantation of tubes 2 randomly distributed over the space occupied by structure 1, as long as the density of tubes 2 remains the same over the entire surface.

Figure 3 shows the detail of an upper part of one of the tubes 2, part where it is embedded through the upper 5 and lower drawers 6. The tube 2 has a truncated section that makes it possible to obtain a flat face. This flat face is equipped with two unidirectional intake 13 and return 11 flaps. The return flap 11 opens from the lower drawer 6 into the tube 2 when the water level in tube 2 drops, while the flap inlet 13 opens from inside tube 2 towards upper drawer 5 when the water level rises in tube 2.

Certain tubes on the periphery of the structure 1 are analogous to the hollow tubes 2 and are, moreover, obstructed in the vicinity of their lower end in a tight manner and in order to trap gas therein.

The device according to this embodiment is anchored to the seabed by anchoring lines via ties not shown. The float level of the device is adjusted by adopting the appropriate number and volume of floats in the periphery and / or by injecting a neutral gas or compressed air into the drawers 5, 6, so that the mean sea level is approximately. midway up the protruding length of the tubes 2. A pressurized gas injection and gas purge assembly can be provided to maintain a pressure in a controlled manner so as to regulate the float height. This set works analogously to the one built into submarines to adjust their depth of immersion. It includes, for example, ballasts from which the water can be expelled thanks to the injection of compressed air.

In figure 2, movements are represented by arrows. At the bottom right, an arrow indicates the orientation of the wave progression or wave wave, that is, from left to right. The right-hand portion of each wave in Figure 2 therefore constitutes a wave front. The corresponding water-free surface 14, in a first set of tubes 2, is in an ascending phase. Conversely, the left portion of Figure 2 of each wave constitutes a wave back. The corresponding water-free surface 12, in a second set of tubes 2, is in a downward phase. The installation can be subjected to any wave spectrum and, in particular, standing waves.

The water-free surface 14 rising inside the tube 2 expels the air through the first intake flap 13, thus feeding the upper drawer 5. The upper drawer 5 thus presents a continuous overpressure taking into account the large number of tubes. 2. Statistically, and thanks to a substantially homogeneous distribution of tubes 2 over the space occupied by structure 1, about half of the tubes 2 see the free water surface 14 rise while the other half of the tubes 2 see the free water surface 12 will descend at each instant. The overpressure in the upper drawer 5 is then, moreover, substantially constant.

The water-free surface 12 descending inside the tube 2 sucks air through the second flap 11 back from the lower drawer 6. The lower drawer 6 thus exhibits a continuous depression, substantially constant and strictly lower than the pressure inside the upper drawer 5.

The global air flow thus formed and represented by various arrows in Figure 2,

- flows from the tubes 2 in which the free water surface 14 rises,

- passes through the first intake flaps 13 to the upper drawer 5,

- passes through a portion of the collector upstream 7 of the conduit 3,

- passes through the working portion 4 activating the turbine 9,

- it is collected by a portion of the collector downstream 8 of the conduit 3,

- is ejected into the lower drawer 6, and

- it is sucked into other tubes 2 in which the water-free surface 12 descends, passing through the second return flaps 11.

The pressure differences ensure air circulation. However, the mean, or static, value of the pressures in the boxes 5, 6 with respect to atmospheric pressure can be adapted to adjust the buoyancy of the structure 1, that is, the position of its waterline. For example, the difference between the depression in the lower drawer 6 and the atmospheric pressure may be substantially equal to the difference between the overpressure in the drawer 5 and the atmospheric pressure. In this case, the buoyancy of the structure 1 is essentially ensured by the floats. In another example, the average pressure in the whole of the structure 1 is maintained above atmospheric pressure. Structure 1 is in overpressure. In this case, the overpressure participates significantly in the Archimedean thrust. Structure 1 can then be devoid of floats.

The buoyancy of the device is ensured, at least in part, by the presence of gas, here air, trapped in tubes 2 and the two drawers 5, 6, the air circulating in a closed circuit between drawers 5, 6 and the duct 3 the tubes 2 of the framework. The stability of the device, its resistance to tipping, is improved providing the periphery of the structure 1 with floats in a way that is not very disturbing to the waves, for example by condemning some tubes of the periphery by clogging their ends as those described hereinafter or even by adding other types of floats.

As a variant, the arrangement of the upper drawer 5 and the lower drawer 6 is reversed so that the upper drawer 5 is downstream of the turbogenerator group 9, 10 while the lower drawer 6 is upstream. The opening direction of the flaps 11, 13 is then reversed.

As a variant, the turbine 9 and / or the generator 10 are arranged in the portion that forms the collector 7 upstream or in the portion that forms the collector 8 downstream, for example by means of tie rods that support them. Turbine 9 drives generator 10 by a rigid horizontal shaft. In another variant, the turbine 9 is arranged substantially on the contact surface between the two drawers 5, 6, for example in a cutout arranged in a wall that separates the two drawers 5, 6 and in such a way that its axis of rotation is substantially vertical , in an area devoid of tubes 2. This arrangement makes it possible to reduce the burden of the work and make it easier to maintain the generator 10 which is then installed on the upper drawer 5 and driven by the turbine wheel 9 via the vertical tree.

The dimensions of the main constituents of the device can be selected with respect to the wave spectrum of the chosen implantation site. The device allows energy recovery for all wave components whose wavelength is comprised between about twice the diameter adopted for the tubes 2 and the overall overall dimension of the platform for the device. The diameter, or the mean diameter, or nominal, if necessary, of the tubes 2 and, therefore, chosen considering the wave spectrum of the site on which the device will be implanted. The diameter is preferably on the order of half the smallest wavelength significantly present in the spectrum. The number of tubes 2, typically several hundred, even several thousand, is defined so that the horizontal sectional area of the set of tubes 2 does not exceed half the surface area of the space occupied by the device.

In the example of Figures 1 and 2, the device is designed to form an autonomous floating platform. As a variant, the device forms a fixed platform integral with the shore or with the seabed, forming, for example, a boardwalk. It can also constitute an attached platform intended to be connected to a floating motor to supply it with electricity. The fixed devices according to the invention can be implanted on sites with a great difference between high and low tides, in which case they produce energy during a part of the tidal change, that is, while the lower ends of the tubes 2 are submerged in water.

In the case where the device forms an autonomous floating platform, it can be moored by an anchoring system, in the proximity of the coast, avoiding, however, the break zones or in a place further from the coast.

As an alternative to an anchor, the floating structure 1 can be held in a fixed place by a mechanism that allows it to slide vertically along a central post fixed to the bottom and passing through the structure 1 and / or along several pillars in the periphery. In this case, the stability to tilting is also ensured by the mechanical guidance of the structure 1 along the pillars fixed to the bottom.

The electricity produced by the generator 10 is brought ashore by a submarine cable to discharge into a network, or it can be self-consumed by the floating motor to which the device is coupled, for example a drilling rig or a ship.

The tubes 2 of the framework can be manufactured from inexpensive materials or from tubes already manufactured today in large series, for example, steel, cast iron, composite materials, plastic materials or reinforced concrete.

The drawers 5, 6 can be manufactured from inexpensive materials such as steel, certain composite materials or reinforced concrete.

In the case of a floating version of the device, the internal air circulating in a closed circuit can be replaced by nitrogen or a gaseous mixture depleted in active oxygen, so that corrosion and the growth of living organisms in the internal parts of the device are prevented. device.

In the case of a fixed version integral with the shore, the wavelengths of the waves that are greater than the main dimension of the platform are likely to create overpressures or depressions of the set of the two caissons 5, 6 since the set of the framework of tubes 2 is then loaded approximately in phase. In order to continue energy production, even in these situations, the lower drawer 6 of the device can be equipped with a high-flow discharge valve set at an opening pressure corresponding to a water head of the order of half that of the free length of tubes 2 under drawers 5, 6. The upper drawer 5, as far as it is concerned, can be equipped with a valve with a large flow rate for the intake of outside air, set at a depression equivalent to this same height of Water. These valves only open in the event of overpressure or depression caused by a rise or fall in phase of the water in most of the pipes.

In the case of a floating version of the device subjected to waves of wavelengths greater than the dimensions of the platform, the latter follows the average movements of the water surface and the risks of overpressure or depression of the drawers 5, 6 due to rising or falling in phase of the water in the whole of the framework of tubes 2 are nonexistent.

The device can be built by assembling several modules, specifically, by juxtaposition. Reference is now made to Figure 4 which depicts a juxtaposition assembly module. A main module, preferably with a polygonal occupied space, comprises, in particular, the turbogenerator group 9, 10. Attached modules having lateral edges or faces in correspondence with those of the main module are assembled to it. Such an annex module is represented in FIG. 4, here in a square shape. The annex module may be devoid of the turbogenerator group 9, 10.

The modules are fixed to each other by their sides. Each module comprises openings 16 arranged in the side faces to face corresponding openings of the neighboring module. The openings 16 allow fluid communication, on the one hand, between the set of upper drawers 5 and, on the other hand, between the set of lower drawers 6 in the assembled state of the device.

In the example described here, the openings 16 are equipped with watertight flanges. These connections have an air flow channeling function that allows the device to function.

A device made up of several modules assembled one to another allows construction in workshops of limited dimensions in the form of a kit to be assembled in the vicinity of the exploitation site or on the site itself. Thus, transportation and transportation to the assembly site is facilitated. Such a design in the form of a kit of modules to be assembled also allows a series of modules to be manufactured while at the same time allowing the shape and extension of the device assembled on site to be adapted according to the situations.

The peripheral sealing of the device on the assembled stage is obtained by sealingly closing the peripheral openings 16 not used, here, by bolted sealing caps.

A device according to the invention has the following advantages with respect to already known devices: it allows energy recovery over a wide spectrum of waves, both in terms of wavelengths and in terms of orientations. It allows, in particular, an efficient energy recovery in situations of conjugated, crossed or stationary waves, agitation or even in case of different orientation of the waves with respect to a possible local marine current.

- it intrinsically understands its own flotation capacity thanks to the gas in its energy recovery circuit. The presence of peripheral floats improves the dynamic stability of straightening against heel in the absence of guidance. When guided vertically along fixed pillars, floats are superfluous.

- The device has a low construction cost since it can be built from products manufactured in existing large series, mainly for tubes. On the other hand, it is devoid of moving parts that work in immersion.

- The device is extremely robust and intrinsically reliable due to its simplicity and due to the fact that it only includes passive mobile mechanical components constituted by clappers, which work in the aerial part of the installation. The device works without a piston or jack system.

- The device has low maintenance costs, its turbogenerator group being emerged and therefore easily accessible.

- The device, particularly when it is buoyant, has excellent resistance to inclement weather and storms thanks to its small packaging and its intrinsic buoyancy.

- The device can be built in a modular way, with each module having dimensions such that they allow easier construction, lifting and transport than a device manufactured in a single piece. This mode of construction allows, on the other hand, by adding modules, to increase the power of an existing installation with a reduced additional investment. Such a modular construction is adaptable at will. - When the gas circuit is closed, a gas or a mixture devoid of oxygen can be incorporated instead of air, which limits the phenomena of internal corrosion and invasion by plant or marine animal organisms.

The invention is not limited to the examples of devices described above, by way of example only, nor to the various combinations of variants, but rather encompasses all the variants that the person skilled in the art can imagine within the framework of the claims that follow.

Claims (17)

1. Wave energy recovery device that includes a hollow structure (1) destined to be maintained above the surface of a body of water, communicating an interior volume of the structure (1) with a turbo-generator group (9, 10), the structure (1) being associated with a multiplicity of hollow tubes (2) open at their lower ends that are submerged in the water, each tube (2) having a first unidirectional flap (13) that opens from inside the tube (2) towards the interior volume, and a second unidirectional clapper (11) that opens from downstream of the turbogenerator group (9, 10) towards the interior of the tube (2), to form an energy recovery loop that works in oscillating water columns, in interaction with the turbogenerator group (9, 10), characterized in that the structure (1) comprises a lower drawer (6) and an upper drawer (5) superimposed, flat, compact, substantially non-deformable, closed and filled with a gas, because the tubes (2) pass through the lower drawer ( 6) and flow into the upper drawer (5) and because the turbogenerator group (9,10) is mounted in a passage that interconnects the two drawers (5, 6), allowing the first clapper (13) of a tube (2) that the gas that is on the water is expelled from the tube (2) towards the upper drawer (5) due to the rise of the water level (14) in certain tubes under the effect of a wave, passing the gas thus expelled through the turbogenerator group (9, 10), then returning downstream to the lower drawer (6) to be admitted by aspiration, through the second clapper (11), in the tubes (2) for which the water level (12) is descending. Device according to claim 1, further comprising flotation members to ensure the maintenance of the structure (1) above the water surface. Device according to claim 2, further comprising anchor lines by means of which the structure (1) can be tied to the seabed. Device according to one of claims 2 and 3, in which the buoyancy members comprise semi-submerged floats arranged on the lower periphery of the structure (1) so that the average level of the water surface is approximately mid-height of the part of the tubes (2) that protrudes below the lower drawer (6). Device according to claim 4, in which at least certain of the floats comprise tubes similar to those of said multiplicity, obstructed at one of their ends. Device according to one of claims 2 to 5, in which the flotation members comprise a set for injection of compressed gas into the drawers (5, 6) associated with one or more gas purges so that the mean internal pressure is kept above atmospheric pressure. Device according to one of claims 2 to 6, in which the structure (1) comprises at least one vertical passage of its own to receive a post fixed to the seabed and which crosses the structure (1) so as to form a vertical guidance by sliding the structure (1) along the post. Device according to one of claims 2 to 6, in which the structure (1) is guided vertically by several posts fixed to the seabed at the periphery of the structure (1) so that a vertical guide is formed by sliding the structure (1) along the posts. Device according to one of the preceding claims, in which the gas circuit is closed. Device according to claim 9, in which the gas consists essentially of nitrogen. Device according to claim 9, in which the gas is depleted in oxygen. Device according to one of claims 1 to 9, in which the gas comprises air. Device according to claim 1, in which the structure (1) is arranged in such a way that it remains substantially immobile with respect to the seabed and / or the shore. Device according to claim 13, in which - The lower drawer (6) comprises a high-flow discharge valve that opens outwards, configured in such a way that it presents an opening pressure that allows evacuating the gas expelled by a rise in phase of the water level in the set of the tubes (2), and / or - the upper drawer (5) comprises a high-flow intake valve that opens inwardly, configured in such a way that it presents an opening depression that allows a suction of outside air generated by a drop in phase of the water level in the set of tubes (2). Device according to one of the preceding claims, in which the passage that interconnects the two drawers (5, 6) is formed by two portions (7, 8) of conduit (3) between which the turbo-generator group (9 , 10). Device according to one of claims 1 to 14, in which the passage that interconnects the two drawers (5, 6) is formed by a cutout in a wall that separates the two drawers (5, 6), including the turbogenerator group (9, 10) a turbine with a vertical axis housed in said cutout. Device according to one of the preceding claims, comprising a combination of upper drawers (5) and lower drawers (6), the upper drawers (5) being in fluid communication with one another, the lower drawers (6) being ) in fluid communication with each other, the turbogenerator group (9, 10) being common to the set of drawers (5, 6) of the combination.